U.S. Pat. Nos. 4,329,017 and 4,479,697 to Kapany et al. disclose a number of fiber optics communications devices for performing a wide variety of monitoring, splitting, switching, and multiplexing functions. The devices are based on the property of a spherical reflecting surface that a point source of light slightly displaced from the center of curvature is imaged with minimal aberration at a point symmetrically located with respect to the center of curvature. The disclosures of the '017 and '697 patents are incorporated by reference.
The '017 patent discloses a single pole/multiple throw switch wherein an input fiber and a plurality of output fibers are disposed with their ends generally coplanar. Switching is effected by tilting the spherical reflector so that the center of curvature is midway between the end of the input fiber and the end of the desired output fiber.
Developments in recent years have presented the need for a fiber optic bypass switch suitable for use in a local area network ("LAN"). In brief, such a switch, located at a node in a fiber optic LAN ring structure would couple an input fiber and an output fiber to a detector and a source, respectively. The switch would have a first, "active" state and a second, "bypass" state. In the active position the input fiber is optically coupled to the detector, and the source is optically coupled to the output fiber. In the bypass state, the input and output fibers are optically coupled to each other, and bypass the source and detector entirely.